1. Field of the Invention
The invention relates to flash memories, and more particularly to data updating of flash memories.
2. Description of the Related Art
A flash memory is a non-volatile memory that can be electrically erased and reprogrammed. Flash memories are primarily used in memory cards and USB flash drives for general storage and transfer of data between computers and other digital products. Flash memory costs far less than EEPROM and therefore has become a dominant memory device. Examples of applications include Personal Digital Assistants (PDA) and laptop computers, digital audio players, digital cameras and mobile phones.
A flash memory comprises a large number of blocks, and each block comprises a plurality of pages for storing data. A flash memory is erased by a unit of a block and programmed by a unit of a page. In other words, when data of the flash memory is erased, all pages of a block of the memory must be erased together. When data is written to a flash memory, the data, however, can be written to a specific page of a block of the flash memory. In addition, data can only be written to a page where no data is stored or a page which has been erased. During flash memory operation, because a flash memory cannot be erased in a unit of a page, when only some pages of a block which has stored data therein is required to be updated with new data, the new data cannot be directly written to the updated pages, and a flash memory controller must specifically handle data updating of the flash memory. Thus, a novel method for handling data updating of a flash memory is therefore required.